Position reproducing system



June 26, 1951 w. J. YOST POSITION REPRODUCING SYS'I'EII Filed April 19,1946 m vE/v ran WILLIAM .1 7057' M 2m A ORA/EV Planes June 2a, 1951UNITED STATES PATENT OFFICE rosrrron 3:5 am srs'rm I William J. Yost,Dallas,

assignments, to Soco Incorporated, New of New York Ten, tssignor, bymesne ny-Vacuum York, N. Y.. a corporation Oil Company,

Application April 19, 1946, Serial No. 663,420 2 Claims. (Cl. 73-305) Myinvention relates to an arrangement for reproducing the position of aconcealed or inaccessible member movable in response to changes inmagnitude of specific gravity, liquid level, or other condition.

In accordance with my invention, there is disposed adjacent and to oneside of the path of movement of the concealed member, which for reasonshereinafter appearing is of magnetizable material, a container for acolumn of liquid in which is submerged an assembly comprising a secondmagnetizable member and a float whose buoyancy is selected or adjustedto balance the weight of the assembly thus to insure that the magneticattraction between the two magnetizable memhers is substantially theonly force tending to effect movement of the assembly.

- Further in accordance with my invention, error otherwise arisingbecause of frictional engagement between the movable members and theirrespective containers is minimized by a stationary magnetizable memberof such construction and disposition that it opposes that component ofthe mutual attraction between the movable magnetizable members which isnormal to their paths of movement.

My invention further resides in features of construction, combinationand arrangement hereinafter described and claimed.

For a more detailed understanding of my invention and for illustrationof an embodiment thereof, reference is made to the accompanyingdrawings, in which:

Fig. 1 is an elevational view, partly in section and with parts brokenaway, of an indicator system;

Fig. 2 on enlarged scale and in cross-section, shows the indicatorassembly of Fig. 1; and

Fig. 3 is a sectional view taken on line 3-3 of Fig. 1.

Fig. 4 is a detail view of parts shown in Fig. 1.

Referring to Fig. 1, the tank l contains a liquid, the variation ofwhose specific gravity or level is to be ascertained exteriorly of thetank. It is assumed that because of the nature of the process orcharacter of the liquid, for example, hydrogen fluoride, it is notfeasible or desirable to employ either a sight glass or any arrangementin which a mechanical linkage is required to extend through the tank.

In accordance with the present invention, there is connected to the tankat a point below the minimum level of liquid therein a container or tubei of length or height which may be approximately equal to the diameterof tank III. The

tube ll may be of metal such as bronze, stainless steel or othernon-magnetic metal resistant to corrosion by the liquid and of strengthcapable of withstanding the pressures involved. In the particulararrangement shown, communication between the container II and tank In iseffected by way of extensions l4 and I! to which there are threadedlyconnected flanges l2 and I3. The latter are held together by bolts l9 orequivalent.

There is disposedwithin the container II for movement axially thereof, amember I6 which, for reasons that hereinafter appear, is of magnetizablematerial and is itself either a permanent magnet or a magnet by virtueof induction from an adjacent permanent magnet or electromagnet. Themagnet I6 is sustainedwithin the liquid column in container II by rod I!to the upper end of which is attached a float I8 which, for purposes ofmeasurement of changes in liquid level. should have suflicient buoyancyto insure that the position of member l6 within container l I shallcorrespond with the level of liquid in tank It. When this float andmagnetic member assembly is to be used for measurement of specificgravity, it should have the same characteristics as a hydrometer float.that is, the 13051- tion of the member Ii within the container II shouldcorrespond with the specific gravity of the liquid in tank l0.

Thus far described, the changes in position of member i6 convey noinformation to an observer because of the opacity of container ll.Accurately and visibly to reproduce the position of the member ii, theris utilized a second, adjacent container 20 which may be of glass orother transparent or translucent material, or which at least is in parttransparent as by provision of a window extending more or less from topto bottom. Within the container 20 there is disposed a column of liquid,for example water, in which is disposed an assembly comprising a float22 and a second magnetizable member 2| which may itself be a magnet ormay be a magnet by virtue of induction from an adjacent permanent magnetor electromagnet.

The buoyancy of the float 22, Fig. 2, is so selected or adjusted bydetermination of the height of the liquid 23 that the assembly 2|, 22has inappreciable or no tendency of itself either to rise or fall in theliquid column within container 20. To avoid the eflect of change inatmospheric pressure upon the buoyancy of float 22, the container 2|] issealed. The space above the liquid therein is in communication with acollapsible bellows 24 whose volume may be adjusted manually by the 3adjusting screw 25 so to adjust the buoyancy of float 22 that theassembly 2|, 22 is balanced.

Preferably and especially when the liquid in tank I, or any of thereaction products in tank "I, are such that any or the elements I5, I!or l8 may be destroyed, the assembly 2 l 22 should have sufllcientresidual weight or buoyance to insure that upon such occurrence theassembly will go and remain beyond scale and so afford positiveindication to an observer of the need for investigation.

With the buoyancy and weight of the assembly 2|, 22 reasonably wellbalanced, it will accurately reproduce, and follow changes in, thepositlon of the concealed inaccessible member IE to which it ismagnetically attracted. When the members l6 and 2| are in correspondingpositions or in horizontal alignment, the attractive force between themis at a maximum and so resists displacement of the indicating member 2|from proper position. This same force, however, tends to pull themembers 16 and 2| against the sides of the respective containers withconsequent likelihood of error due to friction between them and therespective container walls whenever either of members l6 and 2| moves.

To minimize and substantially to eliminate errors of measurement due tosuch frictional forces, there is disposed about the containers H and 20,a stationary member 26 of magnetic material whose length or heightsubstantially corresponds with the range of movement of the members l6and 2|. Member 26 may be a permanent magnet or if either or both of themembers l6 and 2| are permanent magnets, may be a soft iron yoke. In anyevent, the magnetic attraction between the legs of the yoke and therespectively adjacent members l6 and 2| tends to pull the latterhorizontally away from one another, so opposing or balancing thetendency of the members l6 and 2| to move toward one another and intofrictional engagement with the side walls of the respective tubes ii and20. In other words, the member 26 substantially neutralizes thehorizontal component of the magnetic force between the members It and 2|but leaves unimpaired that component of the force which causes theassembly 2|, 22- to move vertically or axially of the container inresponse to an equal and like motion of member 16: the neutralization ofthe horizontal component of the mutual magnetic attraction betweenmembers is and 2| also relieves the former of dragging frictionalengagement with its tube ii for unimpaired sensitivity of response toits actuating float It.

To minimize or effectively cancel the horizontal component of theattractive force between members I5 and 2| without detraction from theaxial component, the yoke member 26 is so positioned and shaped that theattractive force between it and the members It and 2| is substantiallyequal and opposite to their attraction for each other in directionnormal or perpendicular to the axes of the tubes. To attain thisequality or balance of forces, the reluctance of the path of magneticflux between members l5 and 2| is made substantially equal to thereluctance of the path from it to 26 and thence to 2|. This equality isobtainable by proper adjustment or design of the gaps between themagnetic members It, 2| and 25, of the configuration of the pole piecesof member 26, or of the thickness and shape of the central section ofmember 26 which connects the pole pieces thereof.

As above stated, any one or more of members l6, 2| and 25 may be apermanent magnet, preferably of Alnico; alternatively, one or both ofmembers l5 and 2| may be soft-iron and the member 26 the soft-iron yokeof an electromagnet. In event of de-energization of the electromagnet,as by failure of its power supply, the small residual buoyancy or weightof the assembly 2|, 22 will cause it to go beyond scale and so indicatethe inoperative condition of the arrangement and need for investigation.

Although I have specifically described a preferred form of my inventionand a particular use thereof, it shall be understood that changes,modifications and other uses may be made, all, however, within the scopeof the appended claims.

What I claim is:

1. Means for indicating the position of a concealed magnetic membercomprising a closed container for supporting a column of liquid adjacentthe path of movement of said magnetic member and which at least in partis transparent lengthwise of the column, an assembly submerged in Saidcolumn, visible through said container and comprising a second magneticmember attracted to said first magnetic member and a float connected tosaid second magnetic member to form a unit and having passage meanspermitting entry therein of liquid from said column, the buoyancy ofsaid float and the weight of said second magnetic member being at leastin approximate balance, and means for varying the pressure of gas withinsaid container above said liquid column to effect proportional movementof liquid from or into said float through said passage means.

2. A position-reproducing system comprising a magnetic member movable inresponse to changes in magnitude of a condition, a sealed container forsupportin a column of liquid adjacent the path of movement of saidmember, a submerged assembly movable in said column comprising a floatand a second magnetic member attracted by said first magnetic member,said float having passage means permitting entry of liquid from saidcolumn and means connected to said container for varying the pressure onsaid column to adjust the buoyancy of said float for balance against theweight of said second magnetic member.

WILLIAM J. YOST.

REFERENCES CKTED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 995,414 Nault June 13, 19111,363,139 Mason Dec. 21, 1920 2,339,922 Gatewood Jan. 25, 1944 FOREIGNPATENTS Number Country Date 535,746 Germany Oct. 15, 1931 358,462Germany Sept. 9, 1922 20,418 England Nov. 11, 1892

